A plant irrigation device for a potted plant, which includes a hollow stake adapted to be inserted into the soil adjacent to the plant, and a bottle supported on the stake in an inverted position. The bottle is provided with a dispensing cap which has a spout extending down into the hollow stake, and which causes liquid contained in the bottle to drip down through the stake into the soil. A replaceable disc-shaped filter is mounted in the cap which filters sediment out of the liquid through the spout, and which serves to prevent clogging of the spout. The filter also acts as a restrictor which causes the liquid to drip slowly from the bottle.